Manufacture of alkali-earth nitrates and hydrogen sttliid



sas .aren erica ROBERT WILLIAM DAVIS, JR., OF JENKINTOWN', PENNSYLVANIA,

l MANUFACTURE or ALxAm-EARTH minnares AND nrnnoeniv sULFID.-

.Specification of Letters Patent.

Patented Nov. d, 1919.

Application inea December' 13, 1ere. serial No. '136,623'.

To all tohom t may concern:

Be it known that I, ROBERT WILLIAM ADavis, J r., a citizen of the United States, re-

siding in Jenkintown, Pennsylvania, have invented certain Improvements in the Manufacture of Alkali-Earth Nitrates and Hydrogen Suld, of which the following is a rious alkali'earths. The object is -further toprovide means for rendering solutions clean and commercially pure during manufacture, this being accomplished by providing reactions which are satisfactorily complete, thus minimizing both the mother liquor and the' impurities in the crystal salt product. An-

l, other Objectis to providefor reaction prod ucts whichmay -be cleanly filtered away from the liquor to be crystallized or to provide gaseous reaction products which may l i be collected and utilized. A further object is to use mildly reactive substances to carry on the reactions, thus permitting the use of ordinary cheap and simple containers.

According to this invention a strongsolution of an alkali-earth sulfid, for example, barium sulfid, is prepared in the usual way and a suitable amount of the solu tion of a nitrate to be described is added to it. The nitrate solution is slightly in ex-A cess of that theoretically yrequired for the desired reaction. For example, a suitable nitrate is that of aluminium. The nitrate employed' should possess the properties of (1) doubly-decomposing with the sullid, without forming an insoluble sulfid under the conditions of the reaction, (2) decom-` ing drawing, shown in diagrammatic form, partly 1n elevation and partly in section.A

In the drawing, `1 and 2 are, respectively, the pipes for supplying the ,alkali-earth sulid solution and the solution of metal nitrateto the mixing tank 3, the latter con-- taining any suitable'form of stirring apparatus operated by gearing 4. 5 is a pipe for leading the mixed solutions from the tank 3 through an adjusting cock 6 to the reaction vessel 7 1n which the liquor lis boiled. 8 is the fire-box of the reaction vessel with deflectors 9 underneath the pan for heat economy, and 10` is the .exit flue andstack. 22 1s a shaft with paddles 23 attached thereto for the purpose of agitating the liquor during its passage through the reaction vessel in order to more effectually keep 'the liocculent hydrate in suspension. The boiled liquor Hows out from the pan through 'a plpe 13 into any form of holding tank which delivers the liquor' through a pump 14 to a filter-press 15 where the hydrate of aluminium is removed and the solution clarified for crystallization. The filtered liquor passes through a catch tank 16 and thence through a pipe 17 and cocks 18 to crystallizers 19. After crystallization the mother liquor is drawn od through cocks 20 and a pipe` 21 and returned by the latter and pipel 1 ,to the tank 3. A cyclic process is thus established and no solution or salt is wasted. llllis a hood over the reaction vessel for collecting the hydrogen sulfid gas and 12 is the gas exit for conductingV away the gas generated by the reaction.

Inthe practice of this invention I prefer to eiect a thorough mixingof the alkaliearth suld solution with the `solution of a metal nitrate. This is preferably carried out in a tank located above the reaction vessel so that the combined solution may flow by gravity to the vessel. 0f course the mixing may be brought. about either previous to the feeding to the reaction vessel,

incident to thel feeding, or by feeding the two solutions to the reaction vessel separately and effecting the mixing in that vessel. The strength of the solutions will be maintained at approximately the saturation point at 50O C., preferably, although the strength may vary somewhat without interfering seriously with the reaction.

The nitrates of aluminium, magnesium or chromium may be used interchangeably, or any two or more of the salts may be used ture of S0o C. to 100o C., reaction proceeds :M y l v41,321,013

at the same time in any desired proportion.

On mixing the solutions at 50 C., the following reaction probably takes place, although the amount of reaction is optically indeterminate (i) anasleaunonnanzo:

asa(No3)2+a1(on)3-A1 sn)3 As soon, however, as the solution is introduced into the reaction vessel at a temperagradually. The preferred temperature of reaction is from 100-120O C., at which the liquid boils andthe reaction isvigorous. The reaction occurring at the preferred temperature is a completion oftheabove and may be written as follows It will be premised, however, that the spirit of this invention includes the heating in any way and at any temperature that will effect the required reaction for the production of `alkali-earth nitrate. The reaction will proceed at a lower temperature than 100o C., under reduced pressure. the reaction used as a means for carrying out this invention is then as follows when a -Vessel is used having partitions or.-

baiiie plates to check the ow of the solution from the cooler to the hotter portion of the vessel. This latter is the preferred method of feeding'and the discharge in this case is also continuous. I prefer to mechanically -agitate the solution during the time of reaction ton keep the hydrate in suspension,

partly in order that it may easily iiow from the reaction vessel with the solution and partly because the hydrate when in suspension yacts as a nucleus for the separation of more hydrate and the ready completion of the reaction. When using a trough-like reaction vessel a horizontal shaft provided with radiating paddles serves to producel the required agitation. i

.The feature of continuous feeding of the mixed solution economizes heat, 'saves apparatus and provides for a continuous and rather uniform'generation of hydrogen sul.- id gas.y Any of the well known methods maybe employedfor the utilization of this v gas. Practically all of the hydrogen suld is rapidly evolved so that there is -a-ready separation of the gaseous reaction products from the liquid. Collection of the gas'is effected by the sheet-metal hood V 11 .fitted The sum total of of the gas may be accomplished by the usev of a fan in the iue 12, maintaining the vessel undei' slightly reduced pressure.

The reaction proceeds smoothly and little or no undecomposed barium sulfid, and only a trace'of aluminium nitrate, remains in solution. Ordinarily the solution will remain in the reaction vessel long enough to positively complete the reaction by the absoiption of heat, removal of gas, etc., but if an impure alkali-earth nitrate is desired, the reaction need only be approximate, thus leaving some undecomposed barium suld in the solution.

. The hydrates of the metals whose nitrates are used are all insoluble in the finished liquor and are flocculent and easily filtered, A

.settled or otherwise separated from the discharged solution. If it is desired to save this hydrate for use the solution will be f filter-pressed, preferably while in a heated condition, thus preventing premature crystallization and when satisfactorily clear will be conveyed to the crystallizing tanks. The mother-liquor from the crystals will contain practically all of the excess nitrate, owing to its greater solubility over the barium nitrate. It may then be returned to the tank 3 and any contained barium nitrate will be crystallized in the succeeding cycle.

The invention is not strictly limited to the nitrates named, nor to completion ofreaction, nor to crystallizing the salt produced, since these features aie cited more as examples to specify a definite complete process but the intention of the invention' is the manufacture of the alkali-earth nitrates as described, and the manufacture of Ihydrogen sulfid from alkali-earth sulds by the use of a metal nitrate. i'

I. claim:

1. The method of manufacturing alkali i earth nitrate which consists in feeding'zto a reaction vessel a solution of alkali earth'sullid and a solution of a nitrate of, a metal whose hydroxid isinsoluble, causing the solutions to react in said vessel,conducting-v away the gaseous reaction products ,rseparating thesoluble and insoluble reaction' products, andA crystallizing the resultant alkali earth nitrate. l

2. The lmethod of manufacturing alkali earth nitrate which consists in feeding to a reaction vessel a solution of alkali earth sulfid and a solution of a nitrate of a'metal whosehyclroxid is insoluble, causing the solutions to react in said vessel, conducting away the gaseous reaction products, separat- .ing the 'soluble and. insoluble reaction products, crystallizing the resultant alkali earth nitrate, and returning the mother liquor to the reaction vessel.

`3. The method of manufacturing alkali earth nitrate which consists in mixing in a reaction vessel an alkali earth sulldl solution anda solution .of a nitrate of'ametal Whose hydroxi'd is insoluble,

reaction, collecting the gases of reaction, dischargingthe liquid from the reaction vessel, separating the' flocculent hydrate from'the"so'lutio1`1,`l and crYs# tallizingthealkali earth nitrate from said solution.

4. vThe method of manufacturing `alkali i a earth nitrate which consists in mixing in a reaction'wvessel an alkali earth sulid soluftion and a solution of a nitrate of a lmetal whose hydroxid is insoluble, heating the'solution to 1009 to 120 the completion of the reaction, collecting the heating theso-f lution to 100 to'120o G., allowing time for -the completion of the allowing time forrom vthe reaction Wessel, alkali hydrate from thegsolution, crystalliz# ing the alkali. earthfnitrate from the solulioll, 3J11d returning the mother liquor tothe reaction vessel. t f

ases of v reaction, discharging `the liquid separating the! 5.l The method fof manufmuamg hydo;

gen sullid which consists inv mixlngin a re. an alkaliearth.

action vessel a solutionof sulid anda solution of a n'trat'el of a metal Whosel hydroxid is insolu e, mlxed solutions, and emanating therefrom.

name to this specification.

ROBERT-WILLIAM nAvis, JR. 

